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Unlike xylem (which is composed primarily of dead cells), the phloem is composed of still-living cells that transport sap. The sap is a water-based solution, but rich in sugars made by photosynthesis. These sugars are transported to non-photosynthetic parts of the plant, such as the roots, or into storage structures, such as tubers or bulbs. [14]
The cells in vascular tissue are typically long and slender. Since the xylem and phloem function in the conduction of water, minerals, and nutrients throughout the plant, it is not surprising that their form should be similar to pipes. The individual cells of phloem are connected end-to-end, just as the sections of a pipe might be.
Sieve cells are long, conducting cells in the phloem that do not form sieve tubes. The major difference between sieve cells and sieve tube members is the lack of sieve plates in sieve cells. [ 1 ] They have a very narrow diameter and tend to be longer in length than sieve tube elements as they are generally associated with albuminous cells. [ 4 ]
English: xylem (blue) carries water from the roots upwards phloem (orange) carries products of photosynthesis from the place of their origin (source) to organs where they are needed (roots, storage organs, flowers, fruits – sink); note that e.g. the storage organs may be source and leaves may be sink at the beginning of the growing season
The phloem tissue arises from the cell facing outside and consists of sieve tubes and their companion cells. The function of phloem tissue is to distribute food from photosynthetic tissue to other tissues. The two tissues are separated by cambium, a tissue that divides to form xylem or phloem cells.
The presence of vessels in xylem has been considered to be one of the key innovations that led to the success of the flowering plants. It was once thought that vessel elements were an evolutionary innovation of flowering plants, but their absence from some basal angiosperms and their presence in some members of the Gnetales suggest that this hypothesis must be re-examined; vessel elements in ...
It serves several critical functions, including structural support, as the primary vein helps the leaf maintain its shape and structure; food and water transportation, as it contains xylem and phloem tissues that transport water, minerals, and nutrients to and from the leaf; [2] and connection to the stem, as it links the leaf to its vascular ...
XYLEM CELLS DO NOT REQUIRE ENERGY TO CARRY WATER TO DIFFERENT PLANT PARTS. Summary. Description: English: Diagram of phloem tissue in plants. Microscope ...